This invention relates generally to closer apparatus, and more particularly to a new and improved door closer including means for selectively and independently varying opening force, back check force, latching rate, and closing rate of a door.
Door closers known in the prior art range from relatively simple spring loaded pneumatic tube structures to relatively complex hydraulic or pneumatic devices. In many applications, it is desirable to provide a door closer capable of some adjustment with respect to several facets of its operation. Specifically, it is desirable to provide for an adjustment of the amount of resistance provided by the door closer apparatus against opening of the associated door. In this respect, a relatively wide range of adjustment is especially desirable, so that the door closer is useable in conjunction with a considerable range of door sizes and weights. A further desirable adjustment is in the back check force provided, that is, some additional resistance towards the end of the opening motion of the door to avoid damage as, for example, to the hinges, to the door frame or to the door itself due to excessive force being applied during opening. Yet another desirable adjustment is in the closing rate which similarly renders the closer useable in conjunction with a considerable range of door sizes and weights, and also provides a desired rate of closing for a given application. Still another desirable adjustment is in the latch rate of the closer device. By this is meant the application of some additional increment of force toward the end of the closing motion of the door to insure full closure and latching of the associated door while preventing "slamming" which may damage the door or associated parts. It will be recognized that provision for independently adjusting a door closer for each of these areas of operation renders the closer device useable over a broad range of applications.
Yet another desirable feature in a door closer is an adjustable hold open device, for holding the associated door open at a desired position in the travel thereof. Furthermore, some adjustment of the amount of force applied by the hold open device to hold the door open, will accommodate doors of different weights, and also variable loads on doors, such as wind or the like.
Door closers providing some or all of the foregoing adjustments are known in the prior art. However, such door closers have heretofore generally presented at least two significant and related problems or limitations. Specifically, the provision of the foregoing adjustable functions has heretofore required a relatively large and complex apparatus comprising numerous parts. Consequently, many of these prior art door closers have proven unusable in applications where limited space is available. Moreover, such prior art door closer devices have heretofore been relatively difficult to fabricate and assemble, requiring many precision machined parts and therefore leading to increases in labor and expense, often to the point of excess. Such cost factors tend to further limit the desirability of such door closers in an increasingly cost-conscious marketplace.